Table of Content

09 February 2012, Volume 30 Issue 1

Previous Issue    Next Issue

Communication Engineering

Simplified Equalization for Cooperative Communication Systems Based on Distributed Space-Time Codes

XIAO Jun, JIANG Yan-xiang, YOU Xiao-hu

2012, 30(1):  1-6.  doi:10.3969/j.issn.0255-8297.2012.01.001

Asbtract ( 1755 )   PDF (656KB) ( 1930 )  

Related Articles | Metrics

Different from traditional multi-antenna systems, cooperative communication systems are inherently time-asynchronous due to the nature of relay distribution. In this paper, we investigate cooperative communication systems based on distributed linear convolutional space-time codes. An equivalent asynchronous system model is obtained by converting the relays’ transmission delays to a zero vector of the corresponding
generator polynomials. With the banded Toeplitz property of the equivalent channel matrix, we propose a block minimum mean square error equalization method using the Trench algorithm to solve the Toeplitz linear systems. In the proposed equalization method, computation of the high order banded Toeplitz linear system is simplified to that of a low order system. The method avoids high order matrix inversion operations of the
traditional minimum mean square error equalization method, leading to substantial reduction of computational complexity. Simulation results show that satisfactory system performance can be achieved with non-minimumorder non-trace-orthogonal generator polynomials, proper data frame length and large delay.

Resource Allocation Scheme for Heterogeneous Services in Amplify-and-Forward OFDM Relay System

WAN Qing-tao1;2, MA Guan-yi1

2012, 30(1):  7-13.  doi:10.3969/j.issn.0255-8297.2012.01.002

Asbtract ( 1798 )   PDF (1110KB) ( 1233 )  

Related Articles | Metrics

This paper studies a resource allocation problem for heterogeneous services in amplify-and-forward
OFDM relay system under separate power constraints. A resource allocation scheme is proposed to maximize
the data rate of non-realtime service (NRTS) users while satisfying the requirement of realtime service (RTS)
users. The problem is decomposed into two sub-problems: resource allocation for RTS and NRTS. The problem
of RTS is solved with the Lagrangian method, while for NRTS, each subcarrier is allocated to the user with the
best channel gain, and a two-step method is proposed for power allocation. First, the initial power allocation
is done under the total power constraint. The subcarrier power is adjusted to satisfy the separate power
constraints. A low complexity algorithm is proposed for subcarrier set allocation. Simulation results show that
the proposed scheme optimizes the system performance with low complexity while satisfying the requirements
of heterogeneous services users.

Fast Acquisition of Primary Synchronization Signal in LTE Systems

YANG Xiu-mei1;2, XIONG Yong1;2, JIA Guo-qing1;2

2012, 30(1):  14-18.  doi:10.3969/j.issn.0255-8297.2012.01.003

Asbtract ( 1780 )   PDF (706KB) ( 2899 )  

Related Articles | Metrics

A method is proposed to fast acquire primary synchronization signal (PSS) for cell edge users in
long term evolution (LTE) systems. In this method, signals are received in the configured bandwidths of LTE
networks, and the sliding mirror is then correlated. The PSS index is achieved from the local PSS correlation
at peak position after a clear peak value is observed. Analysis and simulation results show that it is applicable
especially to cell edge users in synchronized multi-cell networks to fast acquire PSS with low complexity.
Keywords:

Iterative Detection Decoding Based on Ordered Successive Interference Cancelation for TD-LTE Systems

ZHANG Zheng-yu, QIU Ling

2012, 30(1):  19-24.  doi:10.3969/j.issn.0255-8297.2012.01.004

Asbtract ( 1529 )   PDF (1132KB) ( 1703 )  

Related Articles | Metrics

Abstract: This paper proposes an iterative detection decoding algorithm based on ordered successive interference cancelation (OSIC) for time division long term evolution (TD-LTE) multi-input multi-output (MIMO)
systems. In the algorithm a multiple-codewords transmission mode is used, and the effects of adaptive modulation and coding (AMC) and hybrid automatic repeat request (HARQ) on the detection order are taken into
consideration. Computation complexity of the algorithm is analyzed. Numerical results show that the proposed
method can significantly improve throughput. The performance gain increases with the increase of gaps
between modulation and coding levels of multiple codewords, and the increase of the number of transceiver
antennas.
Keywords:

Energy Optimization and Load Balancing QoS On-Demand Routing Protocol

KUO Yong-hong, GENG Chun-na, CHEN Jian

2012, 30(1):  25-30.  doi:10.3969/j.issn.0255-8297.2012.01.005

Asbtract ( 1541 )   PDF (836KB) ( 1579 )  

Related Articles | Metrics

Abstract: A multi-constrained on-demand protocol, energy optimization and load balancing QoS on-demand
routing protocol (ELQRP), is proposed based on AODV for ad hoc networks. The protocol combines energy
consumption and link load as the QoS parameters to establish a route. Distance information is used to control
broadcasting direction of RREQ packets. Both energy and queue threshold are applied to limit the forwarding
of RREQ packets, reducing unnecessary routing overhead. In the routing maintenance phase, the proposed protocol
uses node energy information to restrict local repairing, preventing power exhausting nodes from building
the routing. All these measures are helpful to optimize the mechanisms of routing selection, forwarding, and
routing maintenance. Results of simulation with NS2 show that ELQRP can effectively improve the network
performance, especially delivery rate, normalized routing overhead and end-to-end delay.

Rate Adaptive Mechanism with Congestion Awareness of DCF Protocol in Ad Hoc Networks

LEI Lei1;2, ZHOU Jin-hua1, ZHU Ying-feng1, LIU Wei-kang1

2012, 30(1):  31-38.  doi:10.3969/j.issn.0255-8297.2012.01.006

Asbtract ( 1359 )   PDF (999KB) ( 1647 )  

Related Articles | Metrics

Abstract: We show why the carrier sense mechanism defined in IEEE 802.11DCF protocol does not support
adaptive multi-rate transmissions in a physical layer, and study the congestion problem in high speed and heavy
loaded multi-hop ad hoc networks. We then propose a rate adaptive mechanism with congestion awareness
of DCF protocol to overcome the congestion problem. According to the channel condition, the receiver can
choose the highest feasible transmission rate, and sends its chosen rate value and congestion information back to the sender. Based on the feedback information from the receiver, the sender can decide whether to transmit data packets or not. Simulation results show that the proposed protocol can effectively solve the congestion problem, and significantly improve the overall throughput of the network.

Resource Optimization for Fairness and Sum Rate Tradeoff in Multiuser OFDM-Based Two-Way Relaying

TANG Lun1, LIU Jin1, LI Guo-jun2, CHEN Qian-bin1, WANG Guang-yu1

2012, 30(1):  39-44.  doi:10.3969/j.issn.0255-8297.2012.01.007

Asbtract ( 1815 )   PDF (790KB) ( 1395 )  

Related Articles | Metrics

Abstract: In OFDM-based cooperative two-way relay networks, sum rate and fairness among user pairs cannot
be achieved simultaneously when these user-pairs exchange their information respectively via an amplify-andforward two-way relay. This paper proposes a novel suboptimal resource allocation scheme to trade off the
proportional fairness and the system sum rate. This scheme is divided into two steps to maximize the sum rate
of the system subject to the constraints of total power and proportionality among user-pair data rate. First,
sub-carrier optimization is processed with equal power among every subcarrier to achieve proportional fairness
and improve the system sum rate. To further improve the sum rate while maintaining fairness, the total power
is allocated to every sub-carrier with an iterative power allocation algorithm. Simulation demonstrates that
the proposed scheme of resource allocation can achieve good tradeoff between proportional fairness and system sum rate.
Keywords:

Enumeration of Balanced Rotation-Symmetric Boolean Functions

ZHANG Peng1, FU Shao-jing2, QU Long-jiang1, LI Chao1;2

2012, 30(1):  45-51.  doi:10.3969/j.issn.0255-8297.2012.01.008

Asbtract ( 1429 )   PDF (528KB) ( 1519 )  

Related Articles | Metrics

 Rotation-symmetric Boolean functions (RSBF) that are invariant under circular translation of
indices have been used as components of different cryptosystems. This paper investigates enumeration of the
balanced RSBFs. Based on some improvements and analysis of the solutions of the correlative equation system,
the lower bound on the number of pr-variable balanced RSBFs is improved, where p is a prime. For a general
odd number n, a lower bound on the number of n-variable balanced RSBFs is provided.

Multi-party Quantum Covert Communication with Entanglement Private-Keys

CAO Dong1;2, SONG Yao-liang1

2012, 30(1):  52-58.  doi:10.3969/j.issn.0255-8297.2012.01.009

Asbtract ( 1486 )   PDF (626KB) ( 1295 )  

Related Articles | Metrics

A novel scheme of quantum multi-party covert communication is proposed. Using a pseudo-random
sequence, the random subset is selected from a set of Greenberger-Horne-Zeilinger (GHZ) shared private-key forencryption. Quantum information is rotated and hidden by disguising it as noise in a quantum error-correcting
code. A subset of detection is constructed and based on the complement of shared private-keys. Based on the
detection scheme of typical error, the private-key can be recycled. Compared to other protocols which require
more private keys, the proposed scheme can significantly reduce key consumption. The ability of eavesdrop
detection is optimized. The optimized scheme is robust to the Trojan horse attacking.

A Family of Protograph-Based LDPC for PR Channels

CHEN Ping-ping1, FANG Yi2, WANG Lin2

2012, 30(1):  59-66.  doi:10.3969/j.issn.0255-8297.2012.01.010

Asbtract ( 1290 )   PDF (1300KB) ( 1225 )  

Related Articles | Metrics

Abstract: For additive white Gaussian noise (AWGN) channel, Jet Propulsion Laboratory (JPL) proposed an AR4JA protograph low density parity check (LDPC) code with good bit error rate (BER) performance and simple hardware implementation. However, such a code is unsuitable for partial response (PR) channels.
This paper introduces a new family of protograph LDPC (near-regular) codes, which are tailored for a typical EPR4 channel of PR channels. The finite-length extrinsic information transfer (EXIT) is also extended to PR systems based on protograph codes of limited code length. In a Monte Carlo simulation over EPR4 channel, the proposed code shows a considerable performance gain both in low- and high-SNR regions compared to regular LDPC codes with column-weight-three, and thus can be viewed as a good code for PR channels.
Keywords:

Robust and Efficient Password-Authenticated Key Agreement Scheme Based on Elliptic Curve Cryptosystem

LIU Tian-hua1, ZHU Hong-feng1, PAN Jeng-shyang2

2012, 30(1):  67-74.  doi:10.3969/j.issn.0255-8297.2012.01.011

Asbtract ( 1332 )   PDF (1052KB) ( 1831 )  

Related Articles | Metrics

Abstract: The paper presents a new password authentication and key-exchange protocol suitable for remote users without verification table and exchanging keys over an untrusted network. The new protocol can resist dictionary attacks by either passive or active network intruders. Against an insider attacker, even weak
password phrases can also be used safely. It also offers perfect forward secrecy, which protects past sessions and passwords against future compromises. Since the user passwords are stored in a form that is not plaintextequivalent to the password itself, an attacker with a smart card cannot use it directly to compromise security and immediately access the host. The proposed protocol is secure, simple, and fast, making it ideal for a wide range of applications in which secure password authentication is required. Compared with the related works, the proposed scheme is more efficient and practical for distributed or portable devices.

Signal and Information Processing

Perpetual Image Hashing Based on Conformal Mapping and Zernike Moments

ZHAO Yan1;2, WANG Shuo-zhong1, YAO Heng1, WU Wei1

2012, 30(1):  75-81.  doi:10.3969/j.issn.0255-8297.2012.01.012

Asbtract ( 1556 )   PDF (3307KB) ( 1559 )  

Related Articles | Metrics

Abstract: We propose a perpetual image hashing method applicable to image authentication and tamper detection. The input image is pseudo-randomly partitioned into blocks, which are resized to become squares of a standard size and mapped to a unit circle by conformal mapping. Zernike moments of the circular-shaped “images” are calculated, and then modified by multiplying an exponent to achieve phase rotation-invariance.
All amplitudes and phases of the modified Zernike moments are concatenated to form an intermediate Hash sequence. The final Hash is produced by pseudo-randomly permuting the intermediate Hash. The purpose of conformal mapping is to include information contained in the corners of square image blocks into the extracted image Hash so that the tamper detection capability is significantly enhanced. Experimental results show that the proposed method is robust against most content-preserving image processing operations. Image blocking allows the tampered regions in the image to be correctly located. Compared to some other techniques, the method has low probabilities of collision and less error in tamper detection.

SVDD Algorithm with Spectral Unmixing for Anomaly Detection in Hyperspectral Images

CHENG Bao-zhi, ZHAO Chun-hui, WANG Yu-lei

2012, 30(1):  82-88.  doi:10.3969/j.issn.0255-8297.2012.01.013

Asbtract ( 1547 )   PDF (876KB) ( 1501 )  

Related Articles | Metrics

 Without considering background interferences, the classical algorithm of support vector data description (SVDD) has relatively low detection probability in hyperspectral anomaly detection. To solve the problem, this paper presented a new algorithm based SVDD, which includes hyperspectral unmixing to separate
target information from complicated background clutter. After spectral unmixing, the error datum includes abundant target information while effectively suppresses the background interference. The error datum is then mapped into a high-dimensional feature space with nonlinear SVDD. By exploiting nonlinear information between the spectral bands of hyperspectral imagery, anomaly targets are detected. The results show that the proposed algorithm can improve detection performance and decrease false alarm probability.

Prostate Ultrasound Image Boundary Extraction Using Discrete Contour Point Set

YUAN Zong-liang1, WANG Yuan-yuan1, YU Jin-hua1, CHEN Ya-qing2

2012, 30(1):  89-95.  doi:10.3969/j.issn.0255-8297.2012.01.014

Asbtract ( 1326 )   PDF (1909KB) ( 1479 )  

Related Articles | Metrics

 A boundary extraction method based on the discrete contour point set (DCPS) is proposed for transrectal ultrasound (TRUS) prostate images. Several features of the prostate boundary are used to search candidate contour points, and a point set is picked up from them as the actual boundary by eliminating nonboundary
candidate points. A coarse prostate boundary is defined by the DCPS and adjusted in a small scale to get a closer prostate boundary using a curve evolution method with a fast level set. Results of experiments for a series of TRUS images show that the proposed method can effectively overcome problems of inhomogeneous intensity distributions inside and outside the prostate, and blur or missing edges, to extract an accurate and fully-formed boundary of the prostate.
Keywords:

Steganalysis of LSB Matching Based on Local Smoothness of Histogram

WANG Ran, PING Xi-jian, ZHENG Er-gong

2012, 30(1):  96-104.  doi:10.3969/j.issn.0255-8297.2012.01.015

Asbtract ( 1708 )   PDF (2011KB) ( 1574 )  

Related Articles | Metrics

 Spatial LSB matching steganography makes the histogram of the embedded images smoother.Based on this, a new steganalytic method that can exploit smoothness changes is proposed. Smooth areas of a given image are chosen based on the value of pixel differences. A total of 15 features include smoothness of image histogram and local co-occurrence matrix, local smoothness and extreme value of pixel difference histograms and co-occurrence differences matrixes, etc., are extracted. The twice embedded process is used to eliminate the influence of different image contents. The Fisher linear discriminator is applied for classification. Results of experiments on the NRCS and UCID databases show that the proposed method has good performance in detecting LSB matching steganography from grayscale images.

Hyperspectral Remote Sensing Estimation Model for Cd Concentration in Rice Using Support Vector Machines

Lü Jie, LIU Xiang-nan

2012, 30(1):  105-110.  doi:10.3969/j.issn.0255-8297.2012.01.016

Asbtract ( 1813 )   PDF (2318KB) ( 1454 )  

Related Articles | Metrics

Research was carried out to explore possibility of using support vector machines (SVM) to estimate Cd concentration from hyperspectral reflectance. Canopy spectral measurements from rice plants were collected using an ASD field spectrometer in the experiment sites. Soil samples and rice samples were collected
for chemical analysis of Cd concentrations. A normalization spectral pre-processing method was employed to improve performance of the estimation model. Wavelet transforms were adopted to denoise the rice hyperspectral. Estimation of Cd concentration was achieved by an SVM approach. Compared to the original
(undenoised) hyperspectrl estimation model, the SVM model based on wavelet transforms yielded promising results with a coefficient of determination of 0.867 4 and a mean square error (MSE) of 0.001 2. The results indicate that it is possible to estimate Cd concentration in rice using wavelet transforms and SVM. This study can provide technical support for large area monitoring of heavy metals stressed crops using hyperspectral remote sensing.